Gettysburg | McPherson’s, Oak and Seminary Ridges | July 1, 1863 | 3:45 to 5:00 pm

After slowing the Confederate advance on the morning of July 1, the Union Army of the Potomac was straining to hold off the increasing number of Confederates gathering to the west of Gettysburg. Elements of the I Corps occupied tenuous positions along McPherson’s and Oak Ridges, and had managed to hold those positions since the mid-morning. Federal reinforcements, however, were slow to arrive. The Army of Northern Virginia, by contrast was growing in strength at an almost exponential rate. Arriving from the North the divisions of generals Robert Rodes and Jubal Early threatened the Federals' exposed left. In the late afternoon, Rodes division smashed into the I Corps troops on Oak Ridge.

At the same time, Gen. Henry Heth’s division, now reinforced by troops under Gen. W. Dorsey Pender, pressed the Yankees on McPherson’s Ridge. Without reinforcements, the Union troops were compelled to fall back and reform on the crest of the ridge dominated by the Lutheran Theological Seminary.